Foil coils for a cathode ray tube yoke



FOIL 001115 FOR A CATHOD'E RAY TUBE Y OKE- Filed March 30, 196.7

14 I5 1 I souRcE OF SOURCE OF HORIZONTAL VERTICAL DEFLECTION DEFL ECTIONSIGNALS SIGNALS f li I N V E N TO R I PETER A. LASKY,

BY g as ATTORN Y.

United States Patent O 3,489,972 FOIL COILS FOR A CATHODE RAY TUBE YOKEPeter A. Lasky, North Syracuse, N.Y., assignor to General ElectricCompany, a corporation of New York Filed Mar. 30, 1967, Ser. No. 627,046Int. Cl. HOlf 5/06 US. Cl. 335-213 6 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND OF THE INVENTION The invention relates to a yoke for acathode ray tube deflection system, and more specifically, it relates tothe' construction of the deflector coils on the yoke.

In cathode ray tubes of the prior art, a yoke with deflection coilscomprising wire windings has been utilized to provide the necessaryhorizontal and vertical deflection of the electron beam to eflect ascanning of the cathode ray tube screen. Although the shapes of theyokes have varied, the deflection coils have generally comprised wireswhich are concentrically wound on the periphery of the core. Even thoughthe deflection achieved by the wire windings is adequate, the wirewindings on the yokes are relatively expensive. Furthermore, the wirewindings when electrically connected to a high frequency source ofhorizontal deflection signals in the conventional television set aresubject to considerably eddy current losses.

SUMMARY OF THE INVENTION It is an object of this invention to provide ayoke for a cathode ray tube deflection system at a reduced cost.

It is still a further object of this invention to provide a yoke for acathode ray tube deflection system wherein the eddy current losses inthe coils of the yoke are minimal.

Briefly stated, and in accordance with certain aspects of thisinvention, there is provided a deflection yoke for a cathode ray tubecomprising a core member adapted to enclose the neck of the cathode raytube and improved deflection coils encircling the core in a plurality ofwindings. The windings comprise strips of conductive foil, perpherallyspaced along the core, to achieve a low cost, low eddy current lossdeflection system.

In accordance with certain and more detailed aspects of this invention,there are provided windings comprising strips of aluminum with ananodized film coating the surfaces of the aluminum strips to provideinsulation between the individual turns of the windings.

BRIEF DESCRIPTION OF THE DRAWINGS The specification concludes withclaims particularly pointing out and distinctly claiming the subjectmatter which I regard as my invention. The invention may also beunderstood from the following description taken in connection with theaccompanying drawings in which:

FIGURE 1 is an end view of a deflection yoke;

FIGURE 2 is an axial view of the deflection yoke of FIGURE 1;

FIGURE 3 is an end view of an alternative deflection yoke; and

3,489,972 Patented Jan. 13, 1970 ICC.

FIGURE 4 is a schematic view of the deflection yoke of FIGURE 1 in aconventional cathode ray tube deflection system.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGURE 1, thedeflection yoke comprises an essentially circular core 10 withdeflection coils comprising a plurality of peripheral windings 11,designated as 11a through 11 appropriately spaced around the core toproduce a magnetic field distribution characterized by good linearity,good focus, and good rectangularity. The windings 11 are formed byencircling segments of the core 10 with strips of a metallized paper orfoil in the form of spiral windings. As is readily appreciated, theindividual turns of the windings must be suitably insulated from eachother and the core, and this may be achieved through one of at least twomethods.

In a first method, the strips of metallized paper or foil; i.e. aluminumor other type of conductive foil, may be coated with an anodized film onone or both surfaces to effect mutually insulated turns of the windings11. This process of anodizing would of course provide insulation at thecore providing the inner surface is anodized.

Alternatively, each strip of aluminum or conductive foil forming thewindings 11 may be wound on the core 10 along with a parallel, discretestrip of insulating material; i.e. paper, to achieve insulation betweenthe individual turns of the windings 11. Again, the inner surface wouldhave to abut the insulating material to insulate the core.

Although the core as shown in FIGURE 1 is essentially circular incross-section and broken along lines 12 and 13, various alternatives areavailable in core geometry configurations. For example, the core 10could be essentially square and comprise a pluarlity of sections.

FIGURE 2 more fully discloses the nature of the windings 11 11a, 11b,11c, 11d, and 11e, including a lead 17 through which the start of thewinding 11b is connected to the finish of the winding 110. The nature ofthe deflection coils may be best seen by reference to windings 11d andlle wherein the various turns take on a laminated appearance. In orderto satisfy the impedance requirements of the deflection system, theexact thickness of the windings or required number of turns may bevaried and should not result in larger overall yoke dimensions thanpreviously known in the art.

FIGURE 3 discloses a hybrid yoke arrangement embodying the invention inthe form of windings 11b, 110, 11g, and 11h in combination withconventional wire Windigs 16. Although the expense of the hybrid yoke asdisclosed in FIGURE 3 is somewhat greater than that disclosed in FIGURE1, the hybrid yoke still reaps the benefit of somewhat lower costs andlow eddy current losses as long as the higher frequency horizontaldeflection signals are applied only to the windings 11b, 11c, 11g, and11h. Application of the vertical deflection signals to the conventionalwire windings 16 produce negligible eddy current losses because of thelower frequency of these signals.

FIGURE 4 illustrates the deflection yoke in combination with atelevision deflection system including a source of horizontal deflectioninput signals 14 connected in parallel with a series combinationcomprising the coils 11h and 11g and a series combination comprising thecoils 11b and to produce horizontal scanning of an electron beam. Toachieve vertical scanning of the electron beam, a source of verticaldeflection input signals 15 is connected in series with the coils 11a,11 lli, 11d, 11e, 11f. Although not shown, it is to be understood thatthe chosen interconnection may be achieved through leads similar to thelead 17.

The configuration disclosed comprises only ten windings. It is of courseappreciated that additional windings and configurations may be providedto achieve the desired deflection required in any particular cathode raytube.

Although specific embodiments of the invention have been shown anddescribed, it is not desired that the invention be limited to theparticular form shown and described and it is intended by the appendedclaims to cover all modifications within the spirit and scope of theinvention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. In a deflection yoke for a cathode ray tube system including a core,the improvement comprising:

deflection coils including a plurality of windings encircling andperipherally spaced along the core, said windings comprising strips ofconductive foil encircling the core in a plurality of turns.

2. The invention of claim 1 wherein said plurality of windings includeinsulation means between each of the plurality of turns of said stripsof conductive foil.

3. The invention of claim 2 wherein said insulation means comprises ananodized film on each of said strips of conductive foil.

References Cited UNITED STATES PATENTS 2,949,593 8/1960 Staley et a1.336206 XR 2,980,874 4/1961 Tarbox 336-206 XR 3,117,258 1/1964 Allen335-213 3,225,269 12/1965 Worcester 336-206 XR 3,348,177 10/1967 Wood335213 OTHER REFERENCES Review of Scientific Instruments, February 1964,pp. 240241, an article by F. R. Crownfield.

GEORGE HARRIS, Primary Examiner US. Cl. X.R. 31375

